O-Ring for sealing between fuel cap and filler neck of automobiles

ABSTRACT

An O-ring for providing hermetic sealing between a fuel tank filler neck and its cap has a single main body with an integrally formed annular lip projecting outwardly from the main body; the lip has an inclined lower surface for contacting a corresponding inclined upper surface of said filler neck, such lower surface defining an angle of inclination θ 1  with respect to the horizontal principal extent of the O-ring body, the filler neck upper surface defining an angle of inclination θ 3  with respect to horizontal, θ 1  being substantially less than θ 3 , the lip being deformable upon tightening of said cap to bring the lip lower surface into hermetically sealing contact with the filler neck upper surface.

BACKGROUND AND SUMMER OF THE INVENTION

This invention relates to O-rings and, more particularly, to an O-ringspecifically designed for providing improved hermetic sealing by beingdisposed between an automotive fuel cap and the fuel filler neck.

Heretofore, O-rings have been utilized for providing sealing between afuel tank cap and the filler neck to which the cap is secured. Thus,referring to FIG. 1, a so-called O-ring 3 is disposed between a fueltank filler neck 1 and a cap 2, for example, in order to keep themsealed hermetically. The conventional O-ring 3 of this type has a roundcross-section as shown in FIG. 2.

However, a conventional O-ring having a round cross-section has a smalldeflection and a small pressure-receiving area and does not come intoclose contact with the filler neck 1 and the cap 2. Hence, it fails toprovide a sufficiently hermetic seal. Accordingly, various O-rings havebeen proposed in the past such as an O-ring 3a whose main body 4a has around cross-section but is equipped with a V-shaped groove 5a as shownin FIG. 3, and an O-ring 3b equipped with a groove 5b which isapproximately V-shaped in the main ring body 4b which has a squaredround cross-section as shown in FIG. 4. (Refer, for example, to JapanesePatent Publication No. 40028/1982.) These constructions increase thedeflection and the pressure-receiving area of the O-rings 3a, 3b andthus improve their hermetic sealing, but their deflection andpressure-receiving area are not yet sufficient. When the internalpressure inside the fuel tank increases, therefore, the fuel is likelyto leak from between the cap 2 and the filler neck 1. In particular,when a large impact is applied to the cap 2 such as in a collision ofthe car, a gap coved occur between the O-ring 3a or 3b and the cap 2 orthe filler neck 1.

It is an object of the present invention to provide an O-ring for a copwhich has an increase pressure-receiving area and deflection, maintainsa sufficient hermetic seal between the cap and the filler neck, andprevents the leakage of fluid such as fuel.

It is also an object of the present invention to provide such an O-ringwhich is particularly intended for use in providing hermetic sealingbetween the fuel cap and the filler neck of automobiles, and whichensures that fuel will not leak even in the event of a collision whichmay apply a large impact force to the cap, or which may cause internalpressure of the fuel.

It is a further object of the invention to provide such an O-ring whichprovides a hermetic seal without any special effort or procedure on thepart of the user; which is inexpensive, simple, and economical tomanufacture; and which is reliable and long lasting in use.

To accomplish the objects described above, in an O-ring sealing the gapbetween a filler neck having an inclined upper surface expanding outwardin a flare and a cap fitted onto the filler neck, the present inventionemploys a construction in which an annular lip is formed integrally withthe main body of the ring so as to project outward, the surface of thelip which comes into contact with the inclined upper surface of thefiller neck is inclined downward towards the center of the ring, theangle of inclination θ₁ between the contact surface of the main ringbody 1 and the horizontal is made smaller than the angle of inclinationθ₃ between the inclined upper surface of the filler neck and thehorizontal, and the angle θ₂ of the groove between the upper surface ofthe lip and the main ring body is approximately 90°.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view of a conventional, prior art O-ring disposedbetween a cap and a filler neck;

FIGS. 2 through 4 are each sectional views of conventional O-ringsaccording to the prior art;

FIG. 5 is a sectional view of the O-ring for a cap in accordance withone embodiment of the present invention;

FIG. 6 is a sectional view of the principal parts showing the O-ring fora cap of FIG. 5 disposed between the cap and the filler neck and the caphas been fastened gently, i.e., before tightening;

FIG. 7 is a sectional view of the principal parts showing the O-ring fora cap of FIG. 5 disposed between the cap and the filler neck, and thecap has been fastened firmly;

FIG. 8 is a sectional view of the principal parts showing the O-ring fora cap of FIG. 5 disposed between the cap and the filler neck, the caphas been fastened and an impact force has then been applied to the cap;

FIG. 9 is a sectional view of the O-ring for a cap in accordance withanother embodiment of the present invention;

FIG. 10 is a sectional view of the O-ring for a cap in accordance with athird embodiment of the present invention.

FIG. 11 is a diagram showing the results of one-sided, i.e., onedirection, tensile pressure tests on the embodiments of the presentinvention; and

FIG. 12 is a diagram showing return leakage angle data after tests onthe embodiments of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring by reference characters to the accompanying drawings, FIG. 5shows the O-ring for a cap in accordance with a first embodiment of thepresent invention.

In the O-ring A for a cap in accordance with the present invention, asformed conventionally of known resilient material, an outwardlyprojecting annular lip 9 is formed integrally with a main ring body 6,and a surface 7 of this lip 9 which comes into contact with an inclinedupper surface 12 of a filler neck 11 is inclined downward towards thecenter of the ring. The angle of inclination θ₁ between the contactsurface 7 and a horizontal surface 6a or horizontal principal extents ofthe main ring body 6 is made to be smaller than the angle of inclinationθ₃ between the inclined upper surface 12 of the filler neck 11 and ahorizontal surface 11a thereof (approximately θ₁ =30° and θ₃ =45° inthis embodiment). The angle θ₂ of the groove between an upper surface 8of the lip 9 and the main ring body 6 is made approximately 90°. Aprotuberance 10 having an annular, arcuate-sectioned shape is formedaround the upper part of the main ring body 6.

The O-ring A for a cap with the construction described above isinterposed between the filler neck 11 (the inclined upper surface 12thereof being shaped as an outward flare) of a fuel tank, for example,and a cap 13, as shown in FIG. 6. Next, as shown in FIG. 7, the cap 13is screwed in tightly so that the lip 9 on the main ring body 6 ispressed into contact with the inclined upper surface 12 of the fillerneck 11, sealing the cap hermetically.

In other words, when the O-ring A for the cap is interposed between thefiller neck 11 of the fuel tank and the cap 13 and is fastened gently asshown in FIG. 6, only the end of the lip 9 comes into contact with theinclined upper surface 12 of the filler neck 11, providing a hermeticseal between the filler neck 11 and the cap 13 to some extent. When thecap 13 is fastened tightly as shown in FIG. 7, however, the end of thelip 9 is pushed up with the fastening and the contact area between thecontact surface 7 of the lip and the inclined upper surface 12 of thefiller neck 11 becomes greater, thereby increasing the hermetic sealbetween them further to a sufficient level. In other words, the angle ofinclination θ₁ of the contact surface 7 of the lip 9, that wasoriginally 30°, increases to 45° as surface 7 of lip 9 is rolled intoprogressively closer and closer conformance with the inclined uppersurface 12 as the cap 13 is fastened and so the pressure-receiving areabetween them thereby increases and provides a sufficient hermeticsealing effect, the pressure-receiving area of seal ultimately beingapproximately the entire contact surface 7 of lip 9, as seen in FIG. 7.

Since the angle of inclination θ₁ of the contact surface 7 of the lip 9and the groove angle θ₂ of the upper surface 8 of the lip 9 are 30° and90°, respectively, the thickness of the lip 9 is reduced and itsflexibility increased so that the inclined upper surface 12 of thefiller neck 11 is pressed strongly into contact with surface 7.Similarly, the arcuate sectioned shape of protuberance 10 is flattenedto increase also the area of contact between protuberance 10 and thecorresponding undersurface of the flange of filler cap 13. Hence thehermetic seal and the reliability between the cap 13 and the filler neck11 are increased further and no fuel can leak from the tank even whenthe internal pressure of the fuel tank rises. In particular, when thecar is in a collision and a large impact force is applied to the cap 13in the direction of the arrow in FIG. 13, a sufficient hermetic seal canbe secured between the O-ring A of the cap and the filler neck 11 due tothe large pressure receiving area between the O-ring A and the fillerneck 11. Needless to say, the wide main ring body 6 and the cap 13 comeinto contact and provide a sufficient hermetic seal between the O-ring Aand the cap 13, and maintain a good hermetic seal between the cap 13 andthe filler neck 11 of the fuel tank always, preventing leakage of thefuel.

Because the main ring body 6 is equipped with the protuberance 10 withan annular, arcuate section about its upper part, the flexibility of themain ring body 6 is increased as a whole and makes the hermetic sealbetween the O-ring A and the cap 13 more reliable, and hence thatbetween the cap 13 and the filler neck 11 of the fuel tank.

FIG. 9 shows the O-ring for a cap in accordance with another embodimentof the present invention. In this embodiment, a main ring body 15 isequipped with a protuberance 14 having an annular rectangular, i.e.,square, section around its upper region which engages the overlying capportion.

Since the protuberance 14 with an annular square section is disposedaround the upper part of the main ring body 15 for increased area ofcontact with the filler cap 13 even before the cap 13 is tightened, theflexibility of the main ring body 15 itself being increased in thisembodiment, and so that the hermetic seal between the O-ring and the cap13 becomes reliable in the same way as in the first embodiment describedabove. This O-ring B of the cap of course has lip 9 with θ₁ being thesame and otherwise of the same configuration as the previous embodimentso that the pressure-receiving area between the cap and the filler neckof the fuel tank and the flexibility increases, thereby improving thehermetic seal between them and preventing the leakage of fuel.

FIG. 10 shows still another embodiment of the present invention, inwhich a main ring body 17 has a cross-sectional shape in which anannular recess 16 is formed on the inner surface, and a protuberance 10having an annular, arcuate section is formed around the upper part ofthe main ring body 17.

Since the main ring body 17 is equipped with the annular recess 16 andthe protuberance 10 having an annular, arcuate section, the flexibilityof the main ring body 17 as a whole increases for appropriatecorresponding O-ring deformation during tightening of cap 13 and so thatthe hermetic seal between the cap and the filler neck can be improvedfurther.

In all the above embodiments, the lip 9 on the main ring body has thecontact surface 7 which has an angle of inclination of 30° so as tocorrespond to and be substantially, i.e., considerably, smaller than theangle of 45° (θ₃) of the inclined upper surface 12 of the filler neck,but the angle of inclination θ₁ of the contact surface 7 of the lip 9may be of course selected in various ways corresponding to the angle ofinclination θ₃ of the inclined upper surface 12 of the filler neck 11.If the angle θ₃ of the inclined upper surface 12 of the filler neck 11is 30° or 40°, for example, the angle of inclination θ₁ of the contactsurface 7 of the lip 9 is made to be 20° or 30°, a value which issubstantially smaller, by from about 10° to about 15°, than θ₃. Inshort, the angle of inclination θ₁ of the contact surface 7 of the lip 9is determined in relation to θ₃ so that the contact surface 7 of the lipas a whole comes into contact with the inclined upper surface 12 of thefiller neck 11 upon the cap being fully tightening.

The groove angle θ₂ of the upper surface is not particularly limited to90° but can be selected to be within the approximate range of 70° to120°, though the resilience of the lip 9 will change to some extent.

The O-ring for a cap in accordance with the present invention can beapplied not only to fuel tanks but also to various tanks storing thereinother fluids such as water.

EXAMPLE

Experimental Method:

The O-ring of the present invention shown in FIG. 5 (hereinafterreferred to as "this invention") and an O-ring having a roundcross-section shown in FIG. 2 (hereinafter referred to as "prior art")were placed in conventional resin caps (17251 01A01) and were subjectedto durability and one-direction tensile tests for evaluation.

Test Items:

1. Initial performance.

2. Gasoline immersion test: Nisseki silver gasoline RT for 72 hrs.

3. Removal test:

(1) after 1,000 removals

(2) immersion in gasoline RT for 72 hrs.

(3) 1,000 removals

4. Heat resistance test: 80° C. for 4 hrs.

5. Cold resistance test:

(1) after immersion in Nisseki silver gasoline RT for 72 hrs.

(2) Held at -30° C. for 30 mins.

6. O₃ composite test:

(1) immersion in "High alum" 2S, at 60° C. for 72 hrs.

(2) at 80° C. for 24 hrs.

(3) at 40° C. and 80 PPHM for 72 hrs.

7. Vibration test:

(1) 3G at 30 cps.

8. Extended gasoline immersion test: Nisseki silver gasoline RT for 10,20 and 30 days.

9. Tensile test (one-direction tensile test).

10. Return leakage test.

Results of Test:

1. The sealing performance at 0.005 kg/cm² was found satisfactory forboth this invention and the prior art.

2. At pressures higher than 0.7 kg/cm², both this invention and theprior art satisfied the rated value and were found satisfactory. As aresult of a comparison of the performance initially and after thedurability test, this invention was found to have an improved quality ofabout 0.3 kg/cm² in comparison with the prior art.

3. No significant difference was found between this invention and theprior art in regard to torque. Hence, both were found to besatisfactory.

4. As a result of the one-direction tensile test, this invention, whichhas a higher initial performance, exhibited a higher durabilityperformance. Hence, this invention was judged to be superior.

5. This invention with its higher resilience was found to have a returnleakage angle about 4 times that of the prior art. Hence, this inventionexhibited an improved performance.

Observations:

This invention was judged to have an improved cold resistance and ahigher sealability during a collision than the prior art, and to besufficiently comparable to the prior art in other respects. Hence, thequality thereof was found to be improved assumedly by the resilience ofthe lip around the outer circumference.

                                      TABLE I                                     __________________________________________________________________________    (Pressure resistance kg/cm.sup.2)                                             __________________________________________________________________________           Initial perfor-                                                        Test item                                                                            mance      Gasoline immersion                                                                      Removal   Heat resistance                                                                         Cold resistance               __________________________________________________________________________    Number of                                                                            30         5         5         5         5                             samples                                                                       Rated value                                                                          0.7 kg/cm.sup.2 × 305                                            This   3.1-3.7 kg/cm.sup.2                                                                      3.3-3.4                                                                            1.9-3.4                                                                            3.1-3.4                                                                            3.1-3.35                                                                           3.4-3.7                                                                            3.4-3.7                                                                            3.2-3.4                                                                            1.0-1.3                  invention                                                                            (average 3.5 kg/cm.sup.2)                                                                (average                                                                           (average                                                                           (average                                                                           (average                                                                           (average                                                                           (average                                                                           (average                                                                           (average                                   3.35)                                                                              2.8) 3.3) 3.2) 3.5) 3.6) 3.3) 1.15)                    Prior art                                                                            3.15-3.9 kg/cm.sup.2                                                                     3.7-3.9                                                                            1.9-3.1                                                                            3.15-3.8                                                                           2.45-2.6                                                                           3.4-3.7                                                                            3.4-3.5                                                                            3.5-3.7                                                                            0.95-1.2                        (average   (average                                                                           (average                                                                           (average                                                                           (average                                                                           (average                                                                           (average                                                                           (average                                                                           (average                                   3.8) 2.3) 3.5) 2.5) 3.55)                                                                              3.45)                                                                              3.6) 1.05)                    Conditions        Initially                                                                          After                                                                              Initially                                                                          After                                                                              Initially                                                                          After                                                                              Initially                                                                          After                                           testing   testing   testing   testing                  __________________________________________________________________________             Test item                                                                            O.sub.3 composite test                                                                  Vibration                                                                             Extended gasoline immersion                 __________________________________________________________________________             Number of                                                                            5         5       5                                                    samples                                                                       Rated value                                                                   This   3.3-3.4                                                                            1.45-1.85                                                                          2.0 kg/cm.sup.2                                                                       3.3-3.6  2.1-3.2                                                                            1.95-2.4                                                                           1.5-1.95                          invention                                                                            (average                                                                           (average                                                                           Measurements                                                                          (average (average                                                                           (average                                                                           (average                                 3.3) 1.7) at predeter-                                                                          3.4)     2.45)                                                                              2.2) 1.65)                                              mined pres-                                                                   sure                                                                          O.K.                                                         Prior art                                                                            3.6-3.8                                                                            1.4-1.5                                                                            2.0 kg/cm.sup.2                                                                       3.6-3.8  2.1-2.4                                                                            1.7-2.0                                                                            1.45-1.6                                 (average                                                                           (average                                                                           Measurements                                                                          (average (average                                                                           (average                                                                           (average                                 3.7) 1.4) at predeter-                                                                          3.7)     2.25)                                                                              1.9) 1.55)                                              mined pres-                                                                   sure                                                                          O.K.                                                         Conditions                                                                           Initially                                                                          After        Initially                                                                              10 days                                                                            20 days                                                                            30 days                                       testing                                                  __________________________________________________________________________

                                      TABLE II                                    __________________________________________________________________________    (torque kgm)                                                                  __________________________________________________________________________    Test item                                                                            Initial performance                                                                       Gasoline immersion                                                                      Removal    Heat resistance                       __________________________________________________________________________    Number of                                                                            30          5         5          5                                     samples                                                                       Rated value                                                                          0.1-0.3 kgm --        0.1-0.3 kgm                                                                              above 0.05 kgm                        This inven-                                                                          0.15-0.2    0.16-0.18                                                                          0.16-0.19                                                                          0.17-0.18                                                                           0.16-                                                                              0.16-0.18                                                                           0.13-0.16                       tion   (average    (average                                                                           (average                                                                           (average                                                                            0.17 (average                                                                            (average                               0.175)      0.17)                                                                              0.17)                                                                              0.175)                                                                              (average                                                                           0.17) 0.15)                                                              0.165)                                     Prior art                                                                            0.16-0.2    0.17-0.20                                                                          0.16-0.19                                                                          0.17-0.18                                                                           0.17-                                                                              0.16-0.18                                                                           0.14-0.16                              (average    (average                                                                           (average                                                                           (average                                                                            0.18 (average                                                                            (average                               0.175)      0.18)                                                                              0.17)                                                                              0.175)                                                                              (average                                                                           0.17) 0.15)                                                              0.175)                                     Conditions         Initially                                                                          After                                                                              Initially                                                                           After                                                                              Initially                                                                           After                                                   testing    testing    testing                         __________________________________________________________________________    Test item                                                                            Cold resistance                                                                         O.sub.3 composite test                                                                  Extended gasoline immersion                        __________________________________________________________________________    Number of                                                                            5         5         5                                                  samples                                                                       Rated value                                                                          below 0.4 kgm                                                                           --        --                                                 This inven-                                                                          0.15-0.18                                                                          0.17-0.18                                                                          0.18-0.20                                                                          0.14-0.18                                                                          0.18-0.20                                                                           0.18-0.19                                                                           0.18-0.19                                                                           0.17-0.19                        tion   (average                                                                           (average                                                                           (average                                                                           (average                                                                           (average                                                                            (average                                                                            (average                                                                            (average                                0.17)                                                                              0.18)                                                                              0.19)                                                                              0.155)                                                                             0.19) 0.185)                                                                              0.18) 0.18)                            Prior art                                                                            0.16-0.18                                                                          0.18-0.22                                                                          0.17-0.18                                                                          0.15-0.16                                                                          0.18-0.20                                                                           0.18-0.20                                                                           0.17-0.19                                                                           0.16-0.19                               (average                                                                           (average                                                                           (average                                                                           (average                                                                           (average                                                                            (average                                                                            (average                                                                            (average                                0.17)                                                                              0.20)                                                                              0.175)                                                                             0.155)                                                                             0.19) 0.19) 0.18) 0.18)                            Conditions                                                                           Initially                                                                          After                                                                              Initially                                                                          After                                                                              Initially                                                                           10 days                                                                             20 days                                                                             30 days                                      testing   testing                                                 __________________________________________________________________________

                                      TABLE III                                   __________________________________________________________________________    (1) Gasoline immersion test  Condition: Nisseki silver RT for 72              __________________________________________________________________________    hrs.                                                                          Initial performance  After testing                                                     0.005 kg/cm.sup.2                                                                    Pressure    0.005 kg/cm.sup.2                                                                    Pressure                                            pressure                                                                             resistance  pressure                                                                             resistance                                 Torque (kgm)                                                                           resistance                                                                           (kg/cm.sup.2)                                                                      Torque (kgm)                                                                         resistance                                                                           (kg/cm.sup.2)                              __________________________________________________________________________    Round O-ring 38150 17135                                                      1 0.20   OK     3.90 0.18   OK     3.10                                       2 0.19   OK     3.70 0.17   OK     2.20                                       3 0.17   OK     3.70 0.17   OK     1.90                                       4 0.18   OK     3.70 0.18   OK     2.40                                       5 0.17   OK     3.70 0.16   OK     1.90                                       -x                                                                              0.18   OK     3.74 0.17   OK     2.30                                       Deformed O-ring 38155 B17135                                                  1 0.18   OK     3.40 0.17   OK     2.30                                       2 0.17   OK     3.30 0.16   OK     1.90                                       3 0.16   OK     3.40 0.16   OK     3.20                                       4 0.18   OK     3.30 0.18   OK     3.20                                       5 0.16   OK     3.40 0.17   OK     3.40                                       -x                                                                              0.17   OK     3.36 0.17   OK     2.80                                       __________________________________________________________________________

                                      TABLE IV                                    __________________________________________________________________________    (2) Removal test                                                                       Conditions:                                                                         1. after 1,000 removals                                                       2. gasoline immersion RT for 72 hrs.                                          3. 1,000 removals                                              __________________________________________________________________________    Initial performance   After testing                                                     0.005 kg/cm.sup.2                                                                    Pressure    0.005 kg/cm.sup.2                                                                    Pressure                                            pressure                                                                             resistance  pressure                                                                             resistance                                Torque (kgm)                                                                            resistance                                                                           (kg/cm.sup.2)                                                                      Torque (kgm)                                                                         resistance                                                                           (kg/cm.sup.2)                             __________________________________________________________________________    Round O-ring 38150 17135                                                      6  0.18   OK     3.30 0.17   OK     2.45                                      7  0.18   OK     3.70 0.18   OK     2.50                                      8  0.17   OK     3.80 0.18   OK     2.60                                      9  0.18   OK     3.15 0.17   OK     2.45                                      10 0.17   OK     3.50 0.17   OK     2.50                                      -x 0.18   OK     3.51 0.17   OK     2.50                                      Deformed O-ring 38155 B17135                                                  6  0.17   OK     3.40 0.16   OK     3.35                                      7  0.18   OK     3.30 0.16   OK     3.10                                      8  0.17   OK     3.10 0.17   OK     3.20                                      9  0.18   OK     3.30 0.16   OK     3.30                                      10 0.17   OK     3.40 0.16   OK     3.15                                      -x 0.17   OK     3.30 0.16   OK     3.22                                      __________________________________________________________________________

                                      TABLE V                                     __________________________________________________________________________    (3) Heat resistance test  Condition: held at 80° C. for 4              __________________________________________________________________________    hrs.                                                                          Initial performance  After testing                                                     0.005 kg/cm.sup.2                                                                    Pressure    0.005 kg/cm.sup.2                                                                    Pressure                                            pressure                                                                             resistance  pressure                                                                             resistance                                 Torque (kgm)                                                                           resistance                                                                           (kg/cm.sup.2)                                                                      Torque (kgm)                                                                         resistance                                                                           (kg/cm.sup.2)                              __________________________________________________________________________    Round O-ring 38150 17135                                                      11                                                                              0.19   OK     3.70 0.16   OK     3.4                                        12                                                                              0.16   OK     3.60 0.15   OK     3.5                                        13                                                                              0.17   OK     3.70 0.14   OK     3.4                                        14                                                                              0.18   OK     3.40 0.15   OK     3.4                                        15                                                                              0.17   OK     3.50 0.15   OK     3.5                                        -x                                                                              0.17   OK     3.60 0.15   OK     3.4                                        Deformed O-ring 38155 B17135                                                  11                                                                              0.19   OK     3.60 0.14   OK     3.7                                        12                                                                              0.19   OK     3.70 0.16   OK     3.6                                        13                                                                              0.17   OK     3.40 0.16   OK     3.4                                        14                                                                              0.16   OK     3.40 0.14   OK     3.5                                        15                                                                              0.16   OK     3.50 0.13   OK     3.7                                         -x                                                                             0.17   OK     3.50 0.15   OK     3.6                                        __________________________________________________________________________

                                      TABLE VI                                    __________________________________________________________________________    (4) Cold resistance                                                           Conditions:                                                                              1. after immersion in Nisseki silver RT for 72 hrs.                           2. held at -30° C. for 30 min.                              __________________________________________________________________________    Initial performance  After testing                                                     0.005 kg/cm.sup.2                                                                    Pressure    0.005 kg/cm.sup.2                                                                    Pressure                                            pressure                                                                             resistance  pressure                                                                             resistance                                 Torque (kgm)                                                                           resistance                                                                           (kg/cm.sup.2)                                                                      Torque (kgm)                                                                         resistance                                                                           (kg/cm.sup.2)                              __________________________________________________________________________    Round O-ring 38150 17135                                                      1 0.18   OK     3.50 0.19   OK     1.05                                       2 0.17   OK     3.60 0.20   OK     1.20                                       3 0.18   OK     3.60 0.19   OK     1.15                                       4 0.17   OK     3.50 0.22   OK     1.00                                       5 0.16   OK     3.70 0.18   OK     0.95                                       -x                                                                              0.17   OK     3.60 0.20   OK     1.07                                       Deformed O-ring 38155 B17135                                                  1 0.17   OK     3.40 0.18   OK     1.25                                       2 0.16   OK     3.30 0.18   OK     1.30                                       3 0.15   OK     3.40 0.17   OK     1.15                                       4 0.18   OK     3.20 0.18   OK     1.10                                       5 0.17   OK     3.30 0.19   OK     1.00                                       -x                                                                              0.17   OK     3.30 0.18   OK     1.16                                       __________________________________________________________________________

                                      TABLE VII                                   __________________________________________________________________________    (5) O.sub.3 composite test                                                            Conditions:                                                                         1. immersed in "High alum" 2S at 60° C.                                for 72 hrs.                                                                   2. at 80° C. for 24 hrs.                                               3. at 40° C. and 80 ppHM for 72 hrs.                     __________________________________________________________________________    Initial performance   After testing                                                     0.005 kg/cm.sup.2                                                                    Pressure    0.005 kg/cm.sup.2                                                                    Pressure                                            pressure                                                                             resistance  pressure                                                                             resistance                                Torque (kgm)                                                                            resistance                                                                           (kg/cm.sup.2)                                                                      Torque (kgm)                                                                         resistance                                                                           (kg/cm.sup.2)                             __________________________________________________________________________    Round O-ring 38150 17135                                                      16 0.17   OK     3.70 0.15   OK     1.40                                      17 0.18   OK     3.80 0.16   OK     1.50                                      18 0.17   OK     3.70 0.15   OK     1.40                                      19 0.18   OK     3.60 0.15   OK     1.50                                      20 0.17   OK     3.70 0.16   OK     1.40                                      -x 0.17   OK     3.70 0.15   OK     1.42                                      Deformed O-ring 38155 B17135                                                  16 0.20   OK     3.40 0.14   OK     1.85                                      17 0.18   OK     3.30 0.15   OK     1.60                                      18 0.20   OK     3.40 0.14   OK     1.80                                      19 0.18   OK     3.30 0.16   OK     1.45                                      20 0.20   OK     3.30 0.18   OK     1.80                                      -x 0.19   OK     3.30 0.15   OK     1.72                                      __________________________________________________________________________

                                      TABLE VIII                                  __________________________________________________________________________    (6) Vibration test  Condition: 3G at 30 cps                                   __________________________________________________________________________    Initial performance  After testing                                                     0.005 kg/cm.sup.2                                                                    Pressure    0.005 kg/cm.sup.2                                                                    Pressure                                            pressure                                                                             resistance  pressure                                                                             resistance                                 Torque (kgm)                                                                           resistance                                                                           (kg/cm.sup.2)                                                                      Torque (kgm)                                                                         resistance                                                                           (kg/cm.sup.2)                              __________________________________________________________________________    Round O-ring 38150 17135                                                      21                                                                              --     OK     3.70 --     OK     2.0 OK                                     22                                                                              --     OK     3.80 --     OK     2.0 OK                                     23                                                                              --     OK     3.70 --     OK     2.0 OK                                     24                                                                              --     OK     3.80 --     OK     2.0 OK                                     25                                                                              --     OK     3.60 --     OK     2.0 OK                                     -x                                                                              --     OK     3.72 --     OK     OK                                         Deformed O-ring 38155 B17135                                                  21                                                                              --     OK     3.40 --     OK     2.0 OK                                     22                                                                              --     OK     3.50 --     OK     2.0 OK                                     23                                                                              --     OK     3.40 --     OK     2.0 OK                                     24                                                                              --     OK     3.30 --     OK     2.0 OK                                     25                                                                              --     OK     3.30 --     OK     2.0 OK                                     -x                                                                              --     OK     3.32 --     OK     OK                                         __________________________________________________________________________

                                      TABLE IX                                    __________________________________________________________________________    (7) Extended gasoline immersion test  Condition: Nisseki silver RT for        10, 20 & 30 days                                                              __________________________________________________________________________    Initial performance  After 10 days                                                     Pressure                                                                             Pressure    Pressure                                                                             Pressure                                            resistance                                                                           resistance  resistance                                                                           resistance                                 Torque (kgm)                                                                           0.005 kg/cm.sup.2                                                                    (kg/cm.sup.2)                                                                      Torque (kgm)                                                                         0.005 kg/cm.sup.2                                                                    (kg/cm.sup.2)                              __________________________________________________________________________    Round O-ring 38150 17135                                                      26                                                                              0.18   OK     3.70 0.18   OK     2.20                                       27                                                                              0.20   OK     3.70 0.20   OK     2.10                                       28                                                                              0.20   OK     3.70 0.20   OK     2.30                                       29                                                                              0.18   OK     3.80 0.18   OK     2.40                                       30                                                                              0.18   OK     3.60 0.18   OK     2.20                                       -x                                                                              0.19   OK     3.70 0.19   OK     2.25                                       Deformed O-ring 38155 B17135                                                  26                                                                              0.18   OK     3.30 0.18   OK     2.10                                       27                                                                              0.19   OK     3.40 0.18   OK     2.10                                       28                                                                              0.20   OK     3.30 0.19   OK     2.20                                       29                                                                              0.18   OK     3.40 0.18   OK     3.20                                       30                                                                              0.19   OK     3.60 0.18   OK     2.50                                       -x                                                                              0.19   OK     3.40 0.18   OK     2.42                                       __________________________________________________________________________    After 22 days        After 30 days                                                     Pressure                                                                             Pressure     Pressure                                                                            Pressure                                            resistance                                                                           resistance  resistance                                                                           resistance                                 Torque (kgm)                                                                           0.005 kg/cm.sup.2                                                                    (kg/cm.sup.2)                                                                      Torque (kgm)                                                                         0.005 kg/cm.sup.2                                                                    (kg/cm.sup.2)                              __________________________________________________________________________    Round O-ring 38150 17135                                                      26                                                                              0.18   OK     2.00 0.16   OK     1.50                                       27                                                                              0.17   OK     2.00 0.18   OK     1.60                                       28                                                                              0.18   OK     1.85 0.18   OK     1.50                                       29                                                                              0.19   OK     1.70 0.18   OK     1.45                                       30                                                                              0.18   OK     1.85 0.19   OK     1.60                                       -x                                                                              0.18   OK     1.88 0.18   OK     1.58                                       Deformed O-ring 38155 B17135                                                  26                                                                              0.18   OK     2.00 0.17   OK     1.70                                       27                                                                              0.19   OK     1.95 0.18   OK     1.80                                       28                                                                              0.19   OK     2.20 0.19   OK     1.50                                       29                                                                              0.18   OK     2.40 0.18   OK     1.80                                       30                                                                              0.18   OK     2.20 0.19   OK     1.95                                       -x                                                                              0.18   OK     2.20 0.18   OK     1.65                                       __________________________________________________________________________

Although the foregoing includes a description of the best modecontemplated for carrying out the invention, various modifications arecontemplated.

As various modifications could be made in the constructions hereindescribed and illustrated without departing from the scope of theinvention, it is intended that all matter contained in the foregoingdescription or shown in the accompanying drawings shall be interpretedas illustrative rather than limiting.

What is claimed is:
 1. For use in providing a seal between a filler neckand a cap, an O-ring characterized by a single main body having anintegrally formed annular lip projecting outwardly from the main body,said lip having an inclined lower surface for contacting a correspondinginclined upper surface of said filler neck, said lip lower surfacedefining an angle of inclination θ₁ with respect to the horizontalprincipal extent of the O-ring body, said filler neck upper surfacedefining an angle of inclination θ₃ with respect to horizontal, θ₁ beingsubstantially less than θ₃, said annular lip being deformable upontightening of said cap to bring said lip lower surface into hermeticallysealing contact with said filler neck upper surface.
 2. An O-ringaccording to claim 1 and further characterized by θ₁, being less than θ₃by an amount sufficient for causing said lip lower surface to comewholly into contact with said filler neck inclined surface upon said capbeing fully tightened.
 3. An O-ring according to claim 2 and furthercharacterized by θ₁ being less than θ₃ by from about 10° to about 15°.4. An O-ring according to claim 3, θ₁ being approximately 30° and θ₃being approximately 45°.
 5. An O-ring according to claim 1 and furthercharacterized by said annular lip having an upper surface defining anangle θ₂ with said main ring body of approximately from 70° to 120°. 6.An O-ring according to claim 1 and further characterized by said mainbody defining an internal surface for surroundingly engaging acorresponding portion of said cap and an upper surface extending beneatha corresponding overlying portion of said cap and said main bodyincluding a protuberance extending upwardly from its upper surface forcontacting said cap overlying portion.
 7. An O-ring according to claim 6and further characterized by said protuberance being of arcuatecross-section which is compressed upon tightening of said cap.
 8. AnO-ring according to claim 6 and further characterized by saidprotuberance being of rectangular cross-section in a region forcontacting said cap overlying portion.
 9. An O-ring according to claim 6and further characterized by said internal surface being provided withan annular recess of arcuate section.
 10. An O-ring according to claim 1and further characterized by said angle of inclination θ₁ increasing toand becoming the same as angle of inclination θ₃ upon tightening of saidcap.